AlGaAs/GaAs HBT linearity characteristics

Communication systems require linear power amplifiers with high efficiency and very low intermodulation distortion. AlGaAs/GaAs heterojunction bipolar transistors (HBT's) were found to have very low intermodulation distortion in power operation. Two-tone tests were carried out on both common-emitter (CE) and common-base (CB) power HBT's. At 7 GHz, the CE HBT showed -20 dBc IM₃ (third-order intermodulation ratio) and 12% power added efficiency (PAE) per tone at the 1 dB gain compression point; IM₃ dropped to -30 dBc at 1.5 dB output power backoff. The CE HBT has lower intermodulation distortion than CB HBT. Load pull data were collected to aid the understanding of the intermodulation. Parameters of the Gummel-Poon model (as used in SPICE) were derived for HBT's based on dc data and small-signal S parameters at various bias points. The accuracy and validity of the model were confirmed by comparison to experimental two-tone results. SPICE predicts that the emitter and base resistances linearize the HBT and reduce the third-order intermodulation distortion. The excellent third-order intermodulation performance of the CE HBT makes it a very attractive choice for linear power amplifiers     

Ultrahigh-efficiency power amplifier for space radar applications

This paper describes a broad-band switch mode power amplifier based on the indium phosphide (InP) double heterojunction bipolar transistor (DHBT) technology. The amplifier combines the alternative Class-E mode of operation with a harmonic termination technique that minimizes the insertion loss of matching circuitry to obtain ultrahigh-efficiency operation at X-band. For broad-band Class-E performance, the amplifiers output network employs a transmission line topology to achieve broad-band harmonic terminations while providing the optimal fundamental impedance to shape the output current and voltage waveforms of the device for maximum efficiency performance. As a result, 65% power-added efficiency (PAE) was achieved at 10 GHz. Over the frequency band of 9-11 GHz, the power amplifier achieved 49%-65% PAE, 18-22 dBm of output power, and 8-11 dB gain at 4 V supply. The reported power amplifier achieved what is believed to be the best PAE performance at 10 GHz and the widest bandwidth for a switch-mode design at X-band.     

Power m.o.s.f.e.t. linear h.f. amplifiers

N-channel silicon m.o.s. transistors for h.f. power applications have been fabricated which are optimised for linear amplification. These devices exhibit 2 W output power and 11 dB power gain at 630 MHz in class-A operation. The intercept point for third-order intermodulation distortion is 48dBm, which is considerably more than the same data obtainable with bipolar transistors.     

Power and linearity characteristics of field-plated recessed-gate AlGaN-GaN HEMTs

Record power density and high-efficiency operation with AlGaN-GaN high-electron mobility transistor (HEMT) devices have been achieved by adopting a field-plated gate-recessed structure. Devices grown on SiC substrate yielded very high power density (18.8 W/mm with 43% power-added efficiency (PAE) as well as high efficiency (74% with 6 W/mm) under single-tone continuous-wave testing at 4 GHz. Devices also showed excellent linearity characteristics when measured under two-tone continuous-wave signals at 4 GHz. When biased in deep-class AB (33 mA/mm, 3% I/sub max/) device maintained a carrier to third-order intermodulation ratio of 30 dBc up to a power level of 2.4 W/mm with 53% PAE; increasing bias current to 66 mA/mm (6% I/sub max/) allowed high linear operation (45 dBc) up to a power level of 1.4 W/mm with 38% PAE.     

Linearised InGaP/GaAs HBT MMIC power amplifier with active biascircuit for W-CDMA application

A high linearity InGaP/GaAs heterojunction bipolar transistor (HBT) monolithic microwave integrated circuit (MMIC) power amplifier is demonstrated using a new structure for a bias circuit for wideband-code division multiple access (W-CDMA) application. A one shunt capacitor is added to a novel active bias circuit and acts as a lineariser improving input P_{1 dB} of 16 dB and phase distortion of 5.1° for the hybrid phase shift keying (HPSK) modulated signal at the 28 dBm output power; the lineariser showing no significant increase of signal loss and chip area. The two-stage HBT MMIC amplifier exhibits a power-added efficiency (PAE) of 37%, a linear power gain of 24.5 dB, and an output power of 28 dBm with an adjacent channel power ratio (ACPR) of -45 dBc, under a 3 V operation voltage     

高功率密度自对准结构AlGaAs/GaAs 异质结双极晶体管

利用各向异性的湿法刻蚀和侧墙隔离技术实现了发射极金属和基极金属的自对准,采用该自对准技术成功地研制出了自对准结构的AlGaAs/GaAs异质结双极晶体管,器件直流电流增益大于20,电流增益截止频率fT大于30GHz,最高振荡频率fmax大于50GHz,连续波功率测量表明：在1dB增益压缩时,单指HBT可以提供100mW输出功率,对应的功率密度为6.67W/mm,功率饱和时最大输出功率112mW,对应功率密度为7.48W/mm,功率附加效率为67%．     

高功率密度自对准结构AlGaAs/GaAs异质结双极晶体管

利用各向异性的湿法刻蚀和侧墙隔离技术实现了发射极金属和基极金属的自对准 ,采用该自对准技术成功地研制出了自对准结构的 Al Ga As/ Ga As异质结双极晶体管 ,器件直流电流增益大于 2 0 ,电流增益截止频率 f T 大于30 GHz,最高振荡频率 fmax大于 5 0 GHz,连续波功率测量表明 :在 1d B增益压缩时 ,单指 HBT可以提供 10 0 m W输出功率 ,对应的功率密度为 6 .6 7W/ m m,功率饱和时最大输出功率 112 m W,对应功率密度为 7.48W/ m m,功率附加效率为 6 7%     

A small chip size 2 W, 62% efficient HBT MMIC for 3 V PCNapplications

This work describes the L-band low voltage (⩾1.6 V) power performance of AlGAs/GaAs heterojunction bipolar transistors (HBTs), their modeling and the design of a 2-W monolithic microwave integrated circuit (MMIC) for 3-V wireless mobile PCN applications (1800 MHz). The two-stage MMIC achieves 62% power-added efficiency (PAE) and 33 dB of linear gain, at a very small chip size of 1.2 mm². To our knowledge this is the best combination of power performance data for wireless applications demonstrated so far for a MMIC. The chip size is about a factor of four smaller than comparable MMIC's known before. The MMIC offers the potential both for low cost production due to small chip size, single voltage supply, and high performance at the same time     

Intermodulation analysis of the collector-up InGaAs/InAlAs/InP HBTusing Volterra series

The intermodulation (IM) distortion of the collector-up InGaAs/InAlAs/InP heterojunction bipolar transistor (HBT) is analyzed using Volterra-series theory. A T-equivalent circuit is used for this analysis. The contribution and interaction of four nonlinear elements: base-emitter resistance, base-emitter capacitance, base-collector capacitance, and common base-current gain are analyzed. For the particular device under investigation, it is found that the cancellation effect is not significant and the base-emitter resistance nonlinearity dominates the third-order IM     

Push-pull circuits using n-p-n and p-n-p InP-based HBT's for poweramplification

P-n-p heterojunction bipolar transistors (HBTs) have been combined with n-p-n HBTs in a push-pull amplifier in order to obtain improved linearity characteristics. Simulations of common-collector push-pull amplifiers demonstrate an improvement of 14 dB in second harmonic content at the onset of power saturation under class-B operation. Further improvement of 14 dB in the third harmonic content is shown by moving to class-AB operation at an expense of 4% decreased efficiency. A common-emitter push-pull amplifier was fabricated using both n-p-n and p-n-p HBTs with external matching and couplers. Testing of the circuit under class-AB conditions showed better third-order intermodulation (by ~9 dBc) and smaller second harmonic content (by ~11 dBc) compared with n-p-n HBTs alone. While the second harmonics were shown to combine destructively in the push-pull amplifier, total cancellation of the second harmonic was prevented by the wide difference in linearity characteristics of the n-p-n and p-n-p HBTs. In addition, the circuit produced over 2 dBm more output power than the n-p n HBT alone at 1 dB of gain compression     

用于W-LAN的5.8GHz InGaP/GaAs HBT MMIC线性功率放大器

介绍了一种应用于W-LAN系统的5.8 GHz InGaP/GaAs HBT MMIC功率放大器。该功率放大器采用了自适应线性化偏置电路来改善线性度和效率,同时偏置电路中的温度补偿电路可以抑制直流工作点随温度的变化,采用RC稳定网络使放大器在较宽频带内具有绝对稳定性。在单独供电3.6 V电压情况下,功率放大器的增益为26 dB,1 dB压缩点处输出功率为26.4 dBm,功率附加效率(PAE)为25%。三阶交调系数(IMD3)在输出功率为26.4 dBm时为-19 dBc,输出功率为20 dBm时低于-38 dBc,在1 dB压缩点处偏移频率为20 MHz时邻道功率比(ACPR)值为-31 dBc。     

基于GaN HEMT的高线性星载Doherty功率放大器设计北大核心CSCD

在射频通信链路中,功率放大器决定了发射通道的线性、效率等关键指标。卫星通信由于是电池供电,对功率放大器的工作效率要求比较高。文章基于GaN HEMT晶体管采用对称设计完成了一款高效率的Doherty功率放大器。测试结果表明:该Doherty功放的功率增益大于29 dB;1 dB压缩点功率(P_(1 dB))大于35 dBm;在35 dBm输出时,其功率附加效率(PAE)大于47.5%,三阶交调失真(IMD3)大于35 dBc;在功率回退3 dB时,其PAE大于37%,IMD3大于32 dBc。     

Optimization of Third-Order Intermodulation Product and Output Power from an X-Band MESFET Amplifier Using Volterra Series Analysis

A third-order analysis for accurately predicting large-signal power and intermodulation distortion performance for GaAs MESFET amplifiers is presented. The analysis is carried out for both single- and two-tone input signals using the Volterra series representation and is based only on small-signal measurements. Simple expressions for the nonlinear power gain frequency response, the output power, the gain compression factor, and the third-order intermodulation (IM/sub 3/) power are presented. The major sources of gain compression and intermodulation distortion are identified. Based on the developed nonlinear analysis in conjunction with the device nonlinear model, a systematic procedure for designing a MESFET amplifier under large-signal conditions for optimum output power and IM/sub 3/ performance is proposed. The method utilizes out of band computed matching compensation through a nonlinear model of the amplifier. The accuracy of the device large-signal and IM/sub 3/ distortion characterization and the practicability of the proposed method are illustrated through comparison between measured and predicted results.     

AlGaAs/GaAs Heterojunction bipolar power transistors

An AlGaAs/GaAs heterojunction bipolar transistor with a total emitter periphery of 320 ?m has been developed for power amplifier applications. For the base contact, Zn diffusion was used to convert the n-type emitter material into p-type with a doping of ?1.0 × 1020 cm?3. Because of the highly doped layer, contact resistivity was extremely low (5 × 10?7 ?cm2). At 3 GHz, a CW output power of 320 mW with 7 dB gain and 30% power-added efficiency was obtained. Under pulsed operation, the output power increased to 500 mW with 6 dB gain and 40% power-added efficiency. With further device structure optimisations, the power performance of heterojunction bipolar transistors is expected to rival, or even surpass, that of the GaAs MESFETs.     

Highly efficient double-doped heterojunction FET's forbattery-operated portable power applications

Microwave power performance of double-doped AlGaAs-InGaAs-AlGaAs heterojunction field-effect transistors (HJFET's) operated at a drain bias of 3 V is described. The fabricated 1.0 μm gate-length HJFET exhibited a maximum drain current of 500 mA/mm, a transconductance of 300 mS/mm, and a gate-to-drain breakdown voltage of 10 V. Power performance for a 14 mm gate periphery device demonstrated a maximum output power of 1.7 W with a 66% power-added efficiency (PAE) at 900 MHz. When the device was tuned for a maximum PAE, it delivered a 71% PAE with an output power of 1.2 W. The results indicate that the developed HJFET has great potential for 3 V battery-operated portable power applications     

Design and fabrication of a wideband 56- to 63-GHz monolithic poweramplifier with very high power-added efficiency

This paper describes the design, fabrication, and measurement of a wideband 60 GHz monolithic microwave integrated circuit (MMIC) power amplifier that has demonstrated via on-wafer continuous wave (CW) measurement a record 43% power-added efficiency (PAE) at an associated output power of 224 mW and 7.5 dB of power gain. At a higher drain bias of 3.5 V, the CW output power increased to 250 mW with 38.5% PAE. Additional performance improvement is expected when the MMICs are tested on-carrier with proper heat sinking. These state-of-the-art first-pass design results can be attributed to: 1) the use of a fully selective gate recess etch 0.12-μm InP HEMT process fabricated on 2-mm-thick 3-in diameter InP substrates with slot via holes; 2) a design based on a novel on-wafer load-pull measurement technique; and 3) an accurate large-signal nonlinear model for InP HEMTs. In order to reach the low cost required for mass production, the same MMIC design was fabricated on an InP metamorphic HEMT (MHEMT) process. The MHEMT version of the MMIC demonstrated 41.5% PAE, with an associated output power of 183 mW (305 mW/mm) and 6.9 dB of power at 60 GHz when measured CW on-wafer. These InP HEMT and MHEMT results are, to our knowledge, the highest PAE and power bandwidth ever reported at V-band     

Power performance of InP-based single and double heterojunctionbipolar transistors

The microwave and power performance of fabricated InP-based single and double heterojunction bipolar transistors (HBTs) is presented. The single heterojunction bipolar transistors (SHBTs), which had a 5000 Å InGaAs collector, had BV_CEO of 7.2 V and J_Cmax of 2×10⁵ A/cm². The resulting HBTs with 2×10 μm² emitters produced up to 1.1 mW/μm2 at 8 GHz with efficiencies over 30%. Double heterojunction bipolar transistors (DHBTs) with a 3000-Å InP collector had a BV_CEO of 9 V and J_{c max} of 1.1×10⁵ A/cm², resulting in power densities up to 1.9 mW/μm² at 8 GHz and a peak efficiency of 46%. Similar DHBTs with a 6000 Å InP collector had a higher BV_CEO of 18 V, but the J _{c max} decreased to 0.4×10⁵ A/cm² due to current blocking at the base-collector junction. Although the 6000 Å InP collector provided higher f_max and gain than the 3000 Å collector, the lower J_{c max} reduced its maximum power density below that of the SHBT wafer. The impact on power performance of various device characteristics, such as knee voltage, breakdown voltage, and maximum current density, are analyzed and discussed     

High-efficiency Ku-band HBT MMIC power amplifier

A Ku-band monolithic HBT power amplifier was developed using a metal-organic chemical vapor deposition (MOCVD)-grown AlGaAs/GaAs heterojunction bipolar transistor (HBT) operating in common-emitter mode. At a 7.5 V collector bias, the amplifier produced 0.5 W CW output power with 5.0 dB gain and 42% power-added efficiency in the 15-16 GHz band. When operated at a single frequency (15 GHz), 0.66 W CW output power and 5.2 dB of gain were achieved with 43% PAE     

High performance fully selective double recess InAlAs/InGaAs/InPHEMTs

InP HEMTs with a double recess 0.12 μm gate have been developed. The material structure was designed to be fully selective etched at both recess steps for improved uniformity and yield across the whole wafer. Devices demonstrated DC characteristics of extrinsic transconductances of 1000 mS/mm, maximum current density of 800 mA/mm and gate-drain reverse breakdown voltages of -7.8 V. Power measurements were performed at both 20 GHz and 60 GHz. At 20 GHz, the 6×75 μm devices yielded 65% maximum power added efficiency (PAE) with associated gain of 13.5 dB and output power of 185 mW/mm. When tuned for maximum output power it gave an output power density of 670 mW/mm with 15.6 dB gain and 49% PAE. At 60 GHz, maximum PAE of 30% has been measured with associated output power density of 290 mW/mm and gain of 7.4 dB. This represents the best power performance reported for InP-based double recess HEMT's     

A +10-dBm IIP/sub 3/ SiGe mixer with IM/sub 3/ cancellation technique

A third-order intermodulation (IM/sub 3/) cancellation technique using a submixer is proposed for a low-power low-distortion mixer. The IM/sub 3/ cancellation is achieved by summing IM/sub 3/ generated in a main mixer and the submixer, which are almost the same amplitude and opposite phase. The mixer was designed to operate at 870 MHz. The proposed technique reduces IM/sub 3/ by 18 dB with a current increase of about 15% and is suitable for low-power applications. The mixer achieved an input-referred third-order intercept point (IIP/sub 3/) of 10 dBm, a gain of 8.7 dB, and an NF of 9.8 dB and dissipates 30 mW from 2.9 V. The IC is fabricated in a SiGe bipolar transistor with f/sub T/= 30 GHz. The IC occupies 1.44 mm/spl times/1.44 mm.